Terraforming Mars will be a formidable task and even though it has only a very weak magnetic field for protection it is also farther from the sun making the solar wind somewhat weaker. Scientists have calculated that a dense enough atmosphere can be formed requiring continuous generation of the necessary gases. But as difficult as making Mars habital is the alternatives are even more difficult. Like bulding an Ark ship to send colonists to the nearest star with liveable planets. If it is important enough to provide humans with a second place to call home in the event of an unstoppable natural catastrophy a way will be found to get the job done.

There wont be any way you could move all those people and be sure you could possibly live on a world that is 2/3 thousand lightyears away. You need food and oxygen and spares and a fuel tank big as jupiter.One way trip 1,825,000,000 years to get there. Dont think you can pack enough toilet paper in the ship.

If we do go to mars sometime in the future we will have to depend on its soil for food production. Heres the problem, different kinds of salts exist in high concentration all over mars where our rovers are. Food/oxygen production is a must without a problem.

Mars water was hot like yellowstone hot water pools but all over in shallow seas. Mars lost its internal heat and magnectic field and it was rather a fast loss. Salts of all types everywhere in very high concentrations. That would mean that in its frozen ices would be high mineral and salt content. The mystery hot water, what heated it. In possibly a 1000 years mars lost whatever atmosphere and water it was much thicker than today and lost soon after its creation maybe 2 billion years ago. If there is liquid water it would be a brine saltier than Monolake california.
I would love to do a Ice core on mars it would explain alot more than ices on earth thinner layers and more history in its ice maybe go back as far as mars water peroid.